Uniquely identifying instances

Hi List,

Last week, as we are going on with development during GSOC, we have run
into a need that may involve the spec.

Client and server may need to uniquely identify an instance to keep track
of its updates and possibly updated relations, but since now the only way
to address an instance on the server is to use its primary key as generated
by the SQL database underneath; this may obviously lead to confusion if a
pk is dropped and later readded assigned to a different instance. Also for
synchronisation purposes between relations stored in the server and in the
client, this may be relevant.
We are discussing the problem here:
https://github.com/HTTP-APIs/hydrus/issues/215

What do you think about? This may be defined at spec-level instead of left
to single implementations?

In general, how have you think to handle the sync of deprecated/changed of
data between the server component and the client component to ensure
consistency?

Best,

Lorenzo Moriondo, from mobile
https://it.linkedin.com/in/lorenzomoriondo